My tip is - you really have to put in place a SYSTEM, not just good intentions when you're actually in a store.
That means learning to cook at least a little, seeking out healthy looking recipes that satisfy both your dietary goals AND taste, and that aren't too tedious to prepare. Then shopping for *only* that stuff, why would you even purchase things you've decided not to eat and bring them into the house?
You can find the "perfect" diet, but if it's something that takes 4 hours of fiddly cooking a day, it's just not gonna happen for 99% of people. Ditto if you can't find enough variety to keep you on track - the "perfect diet" might be stewed prunes, but again good luck eating nothing but that meal after meal, if you make it a week it'd be a miracle.
That being said, DO try to stick with things long enough for your tastes to change. It's tough but you CAN wean yourself off soda, and you will need less of the "flavor assault" and fats over time, you'll appreciate the subtle flavor of good meat and vegetables with minimal seasoning. If you slip, don't get discouraged and quit, get back on track and try again, with modifications if need be.
I'm on an intermediate stage between the random and usually unhealthy stuff I used to eat and the mythical "ideal diet". Most meals are lots of vegetables and a little meat, and I've got snacks down to mostly fruit, nuts&raisins, yogurt and even sometimes vegetables (celery/broccoli w/a bit of peanut butter).
Basics: I can eat all the vegetables I want. Limit the fatty meat and bread/pasta.
So I buy 5 lb bags of frozen vegetables, often the "stir fry vegetables" which give a nice variety. Throw it in a pan add a bunch of no-salt seasoning, put a pork chop or chicken breast on top, little olive oil if it needs it, under the broiler on both sides til the meat is done, BAM done. Once or twice a week I use a salmon steak, or just canned salmon. Ribeye steak a few times a week.
Breakfast is oatmeal or "egg mush" (frozen vegetables + eggs)
When it's hot I often some variety of a cold bean "salad" - olive oil+balsamic vinegar, can of green beans, can of black or garbanzo beans, can of tomato. Usually some kalamata olives. Optional: capers, garlic, whole wheat pasta or oatmeal, red pepper flakes, canned artichoke hearts or heart of palm, mustard, there's a zillion possibilities.
And big bags of broccoli, throw some in with the stir fry veg or bean salad, eat as a salad/snack, whatever. I do alternate this in and out 'cause it's hard for me to use up the whole big bag, and when I overdo it I get tired of it - so find a few things you can alternate when you start to get tired of stuff.
If you've cut down the fat, you WILL need snacks/more frequent meals, so plan those out instead of grabbing potato chips or something nasty. Unsalted nuts+raisins, fruit, a smoothie if you can be arsed to make it and clean the blender (I usually just drink some milk and eat the fruit). Or a greek yogurt + fruit + maybe one or 2 "aussie bites" (rolled oats, flax seed, sunflower seeds etc - kind of like premade "poo bars" see scooby below). Or cottage cheese + fruit or peanut butter. Salsa is great, but even the "healthier" tortilla chips aren't so hot, still looking for a good alternative here 'til then I just try for moderation.
Drinks is plain water, green tea, wine w/dinner, coffee w/breakfast once in a while. Milk+protein powder if I'm on the way to work out/worked out.
It's a regime I can stand eating about 95% of the time and is very time/cleanup efficient. Yeah there's a ton of critiques - sodium from the canned stuff, obviously you'd want to use fresh vegetables as much as possible, but man good luck keeping that in stock and using it up timely if you actually have a job. Too much olive oil, probably a few too many eggs (I can't be arsed to separate and throw out the yolks, plus they're soooo damn tasty). I *try* to buy fresh veg and work more salads into the mix, but damn I just don't have time to keep stopping multiple times a week to do it consistently. It is still a huge step up from where I was. I have some other time saving tricks like lining the pan with foil before broiling, then I don't even have to wash the pan, cooking oatmeal/whole wheat pasta in a thermos so I don't have to boil and watch a pot for half an hour, etc.
I got the egg mush/salmon mush from
http://scoobysworkshop.com/quick-healthy-meals/The bean salad was from Apocalypse Chow - a combination of the "three's a crowd" and "salad nicoise" see if this link works, for me it shows those 2 recipes
https://books.google.com/books?id=VrQAINlgTVQC&lpg=PT166&ots=_nYKNGS9Sn&dq=%22three's%20a%20crowd%22%20%22apocalypse%20chow%22%20garbanzo&pg=PT167#v=onepage&q=%22three's%20a%20crowd%22%20%22apocalypse%20chow%22%20garbanzo&f=false